1. Field of the Invention
The present invention relates to a cap assembly and a secondary battery using the same, and more particularly, to a cap assembly and a secondary battery using the same in which an insulating member is disposed in a partial or an entire of a terminal plate, resulting in improved stability.
2. Description of the Related Art
Rechargeable secondary batteries are economical in comparison to disposable dry cells. In recent years, as low-volume and high-capacity secondary batteries are developed, they are widely used as power supplies for portable electronic/electrical devices, such as cellular phones, camcorders, notebook computers and the like.
The secondary batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, and lithium secondary batteries.
Among them, the lithium secondary batteries are most widely used because of their small size, high capacity, high operating voltage, and high energy density per weight.
The lithium secondary batteries may be classified into can-type lithium secondary batteries and pouch-type lithium secondary batteries depending on shapes of a casing, which accommodates an electrode assembly having a negative electrode plate, a positive electrode plate and a separator. The can-type lithium secondary batteries may be further classified into cylinder-type lithium secondary batteries and prismatic-type lithium secondary batteries.
When the lithium secondary battery is of the can type, the casing is generally formed of a metal such as aluminum and has a cylindrical shape, a prismatic shape, or a pillar shape with rounded edges.
The can has an upper opening through which an electrode assembly is inserted and electrolyte is injected into the can.
The can is then finished by a cap assembly having a size and shape corresponding to the opening of the can, resulting in a sealed bare cell.
When the lithium secondary battery is of the pouch-type, a pouch casing has a space for accommodating an electrode assembly, which is accommodated on a lower surface of the casing.
The lower surface is covered with an upper surface of the pouch casing, and sealing portions are formed at edges of the upper and lower surfaces of the pouch casing and bonded in order to be sealed, resulting in a bare cell.
The bare cell configured above is electrically connected with a protecting circuit board, which includes a protecting device for preventing accident caused by abnormal operation, such as overcharge, overdischarge, overcurrent, and the like.
In general, the electrical connection between the bare cell and the protecting circuit board is made via a lead. Such a secondary battery may be called a core pack.
The core pack is received in a separate casing or a gap of the core pack is filled with a hot-melt resin. The core pack is then subjected to a tubing process with a thin casing and a labeling process, resulting in a battery pack.
In a prismatic-type secondary battery, the conductive terminal plate forming the cap assembly may stab into the electrode assembly or may be brought into contact and short-circuited with the can when the cap assembly finishing the opening of the can is partially distorted and bent toward the electrode assembly by external pressure, causing a stability issue such as a fire and an explosion.
The above information disclosed in this Related Art section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.